Valentines Day Yard Sign - Valentines Day Yard Decorations for Happy Valentine's Day Party Outdoor Lawn Décor with Metal Stakes. Economical and durable, our Coroplast Yard Signs are a staple of outdoor advertising. These outdoor Valentines Decorations Yard signs with Stakes full color direct printed graphics are vertically fluted for use with a Stakes. Coroplast is typically used for yard, parking, real estate, and election signs. They are waterproof.